In the road transport sector, the wheels are mechanical elements that are particularly monitored.
For example, it is important to frequently monitor the wear and tear and the inflation pressure of tires to ensure transport safety.
Also, the screws or the nuts for attaching wheels, and more precisely their tightening torque, should also be monitored regularly.
Actually, because of the vibrations generated by irregularities in the highway pavement and by shocks due to more significant imperfections of said pavement, said attachment elements tend to come loose, which can lead to complete detachment of the wheel relative to the hub.
The detachment of a wheel is dangerous, not only for the driver of the transport vehicle, but also for those drivers of the vehicles located nearby. And, if all of the drivers are safe and sound after the detachment of a wheel, it is the vehicles that are damaged and more particularly the transport vehicle and its load.
Also, it has been noted that in the case of a road transport vehicle, the material consequences of the detachment of a wheel are rarely insignificant.
In contrast, given the number of wheels mounted on the axles of a tractor cab and its trailer, the monitoring of the tightening torque of each of the attachment elements may prove long and tedious for the driver.
In addition, with regard to the many kilometers traveled by the road transport vehicles, the tightening torque of the attachment elements is to be monitored regularly.
However, said monitoring generally is not done as frequently as necessary and, thinking to remedy the problem effectively, some greatly exceed the recommended tightening torque, at the risk of damaging the threads of the attachment elements and even leading to bolt breakage.
Several devices of the prior art have been developed so as to limit or to prevent the detachment of a wheel from a vehicle.
The French patent, of the same applicant and published under the number FR-2897014 and relative to a safety device for a vehicle wheel, thus is known, with said wheel comprising a rim attached to the hub of said vehicle by attachment elements and equipped with a hub cap.
Said device comprises anti-rotational means that assume in particular the shape of caps and that are provided to work with the elements for attachment of the rim on the hub and are integrated with said hub cap.
A first drawback of this first device comes from the necessity of blindly aligning the caps one by one so that they work with the attachment elements during the installation of the hub cap on the wheel, with said hub cap hiding the rim and said attachment elements.
The installation of this first device may prove to be long and complicated when each vehicle wheel is connected to a hub by about ten attachment elements.
In addition, with the integration of the anti-rotational means according to this first device providing a free mounting in rotation of the caps carried by the hub cap, the machining and the adjustments that are necessary to said mounting of the caps considerably increase the manufacturing cost of this first device.
So as to avoid the mounting difficulties and to reduce the manufacturing cost, a second device, presented in the British patent application GB-2325504, provides an arrangement in which the anti-rotational means take the shape of separate elements: with the first elements each working with one of the attachment screws and each comprising a lateral extension, and a second element that can be assimilated with a cover and that comprises at least one outer side wall against which the extensions of said first elements abut to stop the rotation, and therefore the unscrewing, of the attachment screws.
This second device of the prior art is easier and faster to use than the first, in particular if numerous wheels should be so equipped. However, in this second device, the second element ensuring the holding of the anti-rotational means on the wheel is attached by clamping to the rim.
Ultimately, the safety level provided by this second device is also too limited.
Also, the purpose of this invention is to solve the problems of the prior art by proposing a safety device for a wheel of a vehicle, with said device comprising means for locking in rotation attachment elements that are simple and quick to mount on said wheel and that make it possible to ensure integral safety using a locking of the engagement of said device on the wheel.